1. Field of the Invention
The present invention relates to a closing arrangement for ducts having large cross-sectional areas, particularly flue gas ducts for power plants. The arrangement includes at least one flap which is mounted on at least one flap shaft and is arranged either in the duct or within the duct walls. Each flap can be swung by means of at least one drive shaft and lever arrangements composed of crank arms and tightening arms.
2. Description of the Related Art
Various embodiments of the closing arrangement described above are known in the art. Locking arrangements of this type have at least two flaps. When they are used in power plants and particularly in the waste gas or flue gas ducts of power plants, they have extremely large cross-sectional areas of 100 m.sup.2 or more. Thus, significant problems occur when these large flap wings are moved and when they are pressed against the sealing members arranged in the duct. Therefore, it is necessary to provide at least two flaps for closing off the flue gas flow in a duct having such a large cross-sectional area.
In order to absorb the kinetic energy of the flue gases when the wing flaps are being closed and to move the large masses of the wing components, a drive shaft is provided for each wing component. The drive shaft provided for each wing component is rotatably mounted parallel to the pivot axis of the flap. Each drive shaft is provided with a drive which is either located on the inside or on the outside. Since a drive shaft is provided for each flap or wing component, the shafts arranged in the cross-sectional area of the duct form a flow resistance when the locking arrangement is in the open state. Moreover, the drive units arranged on the inside are subjected to the aggressive flue gases in the flow duct. Therefore, a locking arrangement of this type arranged in a duct having such a large cross-sectional area is structurally complicated and, consequently, is also expensive.
It is, therefore, the primary object of the present invention to provide a locking arrangement of the above-described type in which flaps of large size can be moved in a flue gas duct with structurally simple means. Also, the construction and maintenance costs are to be low.